Chlorzoxazone

Chlorzoxazone: muscle relaxant (benzoxazolone).

Chlorzoxazone testing at Vanguard Laboratory: identity, purity and quantity $250 per sample, with results in 3 to 5 business days.

Structure

Chlorzoxazone: 2D structure drawn from the PubChem record (CID 2733).

Compound data

CAS number

95-25-0

Formula

C₇H₄ClNO₂

Molecular weight

169.57 g/mol

Type

Muscle relaxant (benzoxazolone)

Structure and names

Identity: Chlorzoxazone

IUPAC name: 5-chloro-3H-1,3-benzoxazol-2-one

How Vanguard tests Chlorzoxazone

Method for the $250 identity, purity and quantity test: HPLC-UV purity and assay, LC-MS identity, against a reference standard, with results in 3 to 5 business days.

The USP monograph covers identity by infrared and UV spectroscopy, assay by UV spectrophotometry, chromatographic purity by thin-layer chromatography, chlorine content by potentiometric titration, melting range, loss on drying and residue on ignition. Full testing to the USP Chlorzoxazone monograph is available and quoted.

What's reported

Purity, as percent of total peak area
Quantity, against the label claim
Identity, reported as match or no match against the reference standard
With monograph testing (quoted): the monograph’s tests against its limits

Tests and prices

Purity and quantity

$250

Chromatographic purity and mg per unit by the method matched to the compound, identity against a reference standard. 1 unit.

Raw powder purity

$200

Chromatographic purity on bulk powder. 50 mg.

Add-on tests

Add-on test	Price
Identity and impurities
FTIR identity	$90
CHNS elemental analysis (carbon, hydrogen, nitrogen, sulfur)	$125
Chiral purity (where a chiral method exists; new methods quoted)	$250
Water, solvents and salt form
Water content by Karl Fischer	$60
Residual solvents	$150
Counterions: chloride, acetate and TFA	$70
Assay
Assay, % w/w (with raw powder purity; $250 together)	+$50
Metals and conformity
Heavy metals: arsenic, cadmium, chromium, mercury and lead	$150
Conformity: purity and quantity on more units from the same lot	$100 per extra unit
Microbiology (injectables)
Endotoxin	$210
Sterility or bioburden	$150
Container closure integrity (CCI)	$50
Screening
Fentanyl screen	$50

10% off for 10 or more samples.

Need something else? Other tests are available on request.

Sample amount and turnaround

Purity and quantity is $250 per sample (1 unit) and raw powder purity is $200 for 50 mg, with results in 3 to 5 business days. Send the material sealed and labeled, with the label claim and the form it contains.

Salts, forms and compendial references

Chlorzoxazone (CAS 95-25-0)
Tell us the salt or form the label states, so quantity is reported on the same basis.

Questions about Chlorzoxazone testing

Is the $250 test the same as USP monograph testing?

No. The $250 test covers identity, purity and quantity by HPLC-UV for purity and assay, with LC-MS to confirm identity. Full testing to the USP Chlorzoxazone monograph is available and quoted.

Why does the USP monograph use UV for assay while the $250 test uses HPLC?

A UV assay measures total absorbance and cannot tell chlorzoxazone from related compounds. HPLC separates them, so one run gives the purity profile and the quantity.

What impurity is typical for chlorzoxazone?

2-Amino-4-chlorophenol, the starting material and hydrolysis product, is the main related compound. It appears as a separate peak in the HPLC purity profile.

Sources

https://pubchem.ncbi.nlm.nih.gov/compound/2733

Identity facts from the USP monograph header for this compound.

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